1. Field of the Invention
The present invention generally relates to a method for compensating electromagnetic inductive pressure level of an electromagnetic pen, and more particularly to a method for compensating electromagnetic inductive pressure level of an electromagnetic pen with a pressure level compensation value table.
2. Description of the Related Art
Electromagnetic-type input technology applies electromagnetic pens and the input device with induction sensor coils. Electromagnetic pen has advantages of convenient for writing, tip pressure level function, and certain sensing height, and further has side button (as right button or middle button) function as well as electromagnetic pen tail eraser function to increase the functionality and flexibility of use.
Capacitive touch input technology is the mainstream of the input technologies applied to the widely used touch panel. Touch panel module of a touch panel contains a sensor layer which can store charges. Sensors located around the touch panel apply an electric field on the surface of the touch panel and form a capacitor. For a passive touch source, such as a user's finger or a conductive device, when the touch source contacts the surface of the touch panel, electric currents are generated between the touch source and the sensors of the touch panel. Coordinates of touch points on the touch panel can be calculated through different electric currents generated between different sensors and the touch source. Since a passive type touch panel must be used with a conductor, a normal passive type touch panel will not work well when it is used with an non-conductive touch source such as a user with a glove or an non-conductive stylus. In contrary to the passive type touch panel, an active type capacitive touch input technology, sensors generate signal currents to calculate coordinates of touch points on a touch panel when the sensors detect contacts from a touch source, usually a conductive touch source.
Although electromagnetic type input technology has advantages of convenient for writing, tip pressure level function, and certain sensing height as mentioned above, an user's finger(s) or other touch sources will not work and a particular stylus must be used for input operation. Capacitive touch input technology has advantages of allowing the use of variety of touch sources such as an user's finger(s) for input operation and multi-touch gestures for various operations and functions. Thus integrating both electromagnetic and capacitive input technologies into a touch panel will have both advantages thereof and significantly increase convenience of use.
However, the trend of development of touch panel is toward light weight, thin thickness and low production cost. Conventional arrangement of placing an electromagnetic induction substrate beneath a touch panel has the advantage of not affecting optical characteristics of the touch panel but also has disadvantages of increase weight and cost and alignment problem between a display panel and an electromagnetic induction substrate during manufacture processes.
In order to save costs, new technologies directly omit the substrate for supporting electromagnetic induction sensor coils and form electromagnetic induction sensor coils on a peripheral area of a sensor layer of a touch panel. However since sensor coils are only located on the peripheral area of the touch panel, signal strengths of a stylus or an electromagnetic pen on different locations inside the sensor coils would vary which also cause error on pressure level values of the stylus or electromagnetic pen. Therefore, it is necessary to provide a solution to solve the problem of the pressure level value error resulting from the stylus or electromagnetic pen on different locations inside the sensor coils.